Automatic compensator for magnets



(No Model.) 7 2 Sheets-Sheet 1.

E. THOMSON.

AUTOMATIC OOMPENSATOR FOR MAGNETS. No. 350,956. x Patented Oct. 19, 1886.

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(No Model.) 2 Sheets-Sheet 2.

E. THOMSON.

AUTOMATIC GOMPENSATOR FOR MAGNETS. No. 350,956. Pa 11 0t. 19, 1886. .3.

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UNITED STATES PATENT rEicE.

ELIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- IIOUSTON ELECTRIC COMPANY, OF CONNECTICUT. v

AUTOMATlG COMPENSATOR FOR iJlAGhii-il EPEGIEECATION forming part of Letters Patent No. 350,956, dated Cotober 19,1886.

Application filed August 11, 1884. Serial X0. 140.229. (No model.)

To all whom it Duty concern.-

Be it known that I, ELIHU THoMsoN, a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Mas sachusetts, have invented certain new and useful Improvements in Automatic Compensators for Magneto-Electric Lamps, of which the following is a specification.

The object of my invention is to provide a IC compensation for changes of temperature and consequent changes of resistance in the helices of electro-magnets used for regulating or con trolling purposes in electric-arc lamps and other electric apparatus. In operating electricarc lamps especially a source of derangement is found to exist in the changes of temperature of the copper coils, especially for the dcrivedcircuit magnet, such changes occurring both during operation from the heating effects of the electric current traversing the coils, and also under conditions of change in the temperature of the atmosphere. There results from this a change in the resistance of the magnet-coils, and since in adifferential or other lamp depending upon a derived-circuit magnet a delicate balance exists between the force of the magnet or other device for separating the carbons and that of said derivedcircuit or feed-regulating magnet,-such change 3: of temperature will disturb this balance and necessitate a readjustment after current has been put on or -after a change in the temperature of the surrounding atmosphere.

My invention in its simplest form decreases 5 this difficulty and necessity for readjustment, and in its more complete form practically avoids any changes of adj ustment or action from changes of temperature in the coils of the mag net.

In describing my invention I will make use of simple diagrams, leaving out all parts of the lamp mechanism not immediately concerned in the action.

In the accompanying drawings, Figure 1 is 5 a diagram illustrating the principle of my in vention. Figs. 2, 3, t, 5, and 6 illustrate various ways of carrying the invention into prac tice.

At A, Fig. l, is indicated the are between the positive and negative electrodes of an elec trio-arc lamp, while at m is indicated the en- S change.

trance or positive wire, and at y the negative or exit wire for that portion of the circuit containing the lamp.

1) indicates the main or principal circuit 5 coil or magnet for a lamp, and S the derivedcircuit coil.

G indicates a resistance of German silver wire, or of other material whose resistance is not practically changed by changes of tempera 5o ture, or whose changes of resistance, if any, are different from those in the branch contain ing coil D with the same changes of temperature. The portions of circuit, including the coil D and resistance G, form branches or derivations of the general circuit, as is obvious on inspect-ion, and the coil D and resistance G form each a branch around the portion of circuit containing the other. The coils D and S are, as usual, of copperor like material, whose resistance changes with changes of heat. By change of temperature the resistances of D and. The amount of current that passes through S would therefore, with a given length of are at A, vary according to temperature; 7 but as the coil S is ordinarily used to adjust the are it is manifest that it will not act uniformly unless its resistance be constant or compensation be made. This compensation in a system in which the coils D and Spull against one another can be effected by modifying the current passing through D. which result is obtained by the presenceof the German silver shunt, as shown. As D increases in temperature at the same time that S does, 8 its resistance also increases and diverts more current through G, the latter being of practically constant resistance. A weakening of the magnetism of D therefore occurs simultaneously with the weakening of S, due to increased 0 resistance.

In the arrangement of devices just described the compensation for the changes of resistance in the derived-circuit coil is effected by the action of the currentin the branch containing the coil D, such coil being the coil of an electromagnet, whose changes of power take place simultaneously with the changes of power of S, and are of such a nature as to compensate for the weakening or strengthening ICO of S, as the case may be.

In Fig. 1, the compensation is effected by magnet-coil D, at the same time that coil S weakens, this being rendered necessary by the fact that said coils act in opposition to one another. Either or both of the branches containing resistances that vary, as described, un

change in the flow of current on the circuit on which they are placed. I

The compensation effected by the arrangement shown in Fig. 1 is only partial; but better results can be obtained. by making a coil in the branch containing resistance G act as the compensating or auxiliary coil'that corrects the changes of power of magnet S. This may be conveniently effected by making the resistance G into the shape of a magnet coil, which shall act magnetically to assist the magnet S. When so used, it can be applied to non-differential systems. Fig. 2 shows its application in a simple way. The coils D and S are arranged to act oppositely, in the wellknown way, to adjust the are at A, D separating and S causing an approach of the carbons. The German silver coil G is in a derivation or branch. around coil D, of copper, and acts magnetically or otherwise to assist the magnet-coil S, as indicated. In this figure coil G is wound upon a separate magnet-core; but it might be wound on the same core. The proper proportions between D and G to be used vary with all other proportions; but, however used, (provided the combined magnetic strengths of S and G do not overcome that of D, unless an arc of proper length to feed is obtained,) a greater or less compensa-' tion is effected, and the principles of my invention are present.

In Fig. 3 coils D and G are wound oppositely or differentially upon the same core, and the magnetic pull due to superior effect of D acts in opposition to S and adjusts the arc. The current enters at X, branches, and passes through coil D, of copper, .and coil G, of German silver, in opposite directions about the core of the magnet, and reunites before reaching the are A. Coil S is in derived circuits about the arc. The current diverted into G, on an increase of temperature, reduces the current in D, and also cuts down the strength of the magnet, so as to compensate for the increase of resistance in S. a

In Fig. 4 coil G is wound along with S and in the same direction upon the same core. The effect is the same as in Fig. 2.

In Fig. 5 all three coils are wound as a single magnet or solenoid, D being wound in opposite direction to S and G, or, rather, the current being passed in such opposite directions. The latter modification is at once very simple and effective. Many other combinations of parts are possible.

The operation is as follows: The coil D, being traversed by the direct current, acts to separate the-carbons until restrained by the counteract-ing effect of S-the derived-circuit coil; but should the coil S become heated (D partaking of a like increase of temperature) the power of S is weakened, because it carries a relatively smaller current than before. This is compensated for, however, by the increased effect of G assisting S. The current passing through G increases because of the increase of resistance of D upon increased temperature.

The efiect of D is thereby weakened and that vof G, or virtually of S, strengthened. The

amount of such compensation is governed by the relative resistances of the parts and their number of convolutions. An example will suffice. Let the resistance of G and D, when cold, be made equal, but let D have three and one-half times the number of convolutions that G has about the core. These proportions will give practical compensation with copper wire and German silver, as described. In the arrangements illustrated in Figs. 2, 3, 4, and 5 it will be observed that the compensation is obtained by the action of magnet-coils in both branches of the circuit containing materials, respectively, whose variation of resistance for a given change of temperature are respectively different. Fig. 1 illustrates the compensating coils or magnets placed in the branch containing the resistance whose changes are the greatest for a given change of temperature. Such coil might, however, be placed in the branch whose changes of resistance are the less, care being taken to apply the magnetic effects of such coil in such way as to balance or compensate for the changes in the magnetic effects of the coil S. For instance, where the'system is non-differential, or when the actions of D and S are not opposed, or when the regulation of the arc is obtained by the action of a derived circuit, S, only, the same principles may be rial, affected by changes of temperature is in multiple arc with silver-wire coil. .D and S are supposed to change temperatures together and to a, like degree, and may be associated closely to that end. It is more difiicult to cffeet a complete compensation in such case, for

the effect of the coil G must begreatly increased, but a partial compensation is readily effected.

What'I claim as my invention is 1. The combination, with the feed-regulating helix of an electric lamp, of two branches or derivations of the main circuit containing, respectively, materials whose changes of re sistance for given changes of temperature are different, and a compensating-magnet coil for assisting or opposing the action of the regulating-helix,so as to compensate for the changes of power of the same with changes of temperature, said compensating-coil acting on a difference in the ratio of fiow of current in the said branches on achange of temperature affecting the same.

2. The combination, with the feed-regnlating helix for an electric-arc lamp, of a coinpensating-niagnet coil placed in a branch to a portion of the circuit containing material whose changes of resistance for a given change of temperature are different from those occurring in the branch of the said magnet-coils, so that a variation of resistance for a given change of temperature will disturb the ratio in which the current flows through said coil, and the portion of circuit to which it forms a branch, as and for the purpose described.

3. The combination, with a teed-regulating helix, of a magnet-coil assisting or Opposing the action of the same, as the case may be, and two branches or derivations of the main circuit, one containing said magnet-coils and the other a material whose specific resistance rises unequally with the resistance of the branch containing the coils for agiven change of temperature.

at. The combination, in an electric-arc lamp, of a derived circuit helix, a compensating main-circuit helix, and a resistance in a bra nch around the same, one of the derivations of the circuit containing said helix, and resistance embracing a material whose resistance does not materiall; change with an increase of tei'nperature.

5. The combination, with the direct and derived circuit coils in an electric lamp, of a constant resistance in a branch around the former. said resistance constituting a magnetcoil which assists the derived-circuit coil in its feed-controlling action.

6. The combination, in an electric-arc lamp, of a feed-regulating magnet in a derived circuit around the arc, and a branch around a portion of the main circuit, said branch forming a sliunt of approxiinately-constant resistance around a resistance which varies in amount with an increase of temperature.

7. The combination, substantially as de scribed, of a regulating-magnet in a main circuit, a-regulating-magnet in a branch, and a compensating-coil of approximately constant resistance for different temperatures in a branch around the main-circuit magnet.

8. The combination, with a magnet wound with wire, whose resistance changes with changes of temperature, of a second magnetiZing-coil formed of a material whose resistance is approximately constant under changes of temperature, and a branch around said magnet-coil, containing a resistance that varies with changes of temperature, as and for the purpose described.

9. The combination, with a derived-circuit magnet, ofa second magnetizinghelix, of Ger man silver or its equivalent, as described, placed in the main circuit, and a branch around said helix,having a resistance that increases with a change of temperature.

10. The combination, in a device for compensating for changes of a magnets strength caused by changes in the temperature of its coils, of two branches in the circuit to said magnet, said branches differing from one an other in their change of resistance under similar changes oftemperature, and one of them containing a magnet-coil acting in combina-v tion with the magnet whose changes of resistance are to be compensated, as and for the purpose described.

11. The combination,with a derived-circuit electro-inagnet, of two branches or derivations of the main circuit, containing, respectively, materials whose change of resistance for given changes of temperature is differcut, and a magnetcoil for producing an assisting or opposing action commensurate with the change in the ratio of flow in the two branches so as to compensate for the changes of resistance in the coils of said derived-circuit electromagnet.

Signed at Lynn, in the county of Essex and State of Massachusetts, this 1st day of August, A. D. 1884.

ELIHU THOMSON.

W'itnesses:

O. V. ROBERTS, W. S. HUNTLEY. 

